Andrea Stander of Rural Vermont helped organize a protest Sept. 20 in Burlington, prompted by the appearance of a Monsanto vice president at a feed dealers meeting. / Dan D'Ambrosio, Gannett

by Dan Dâ??Ambrosio, USA TODAY

by Dan Dâ??Ambrosio, USA TODAY

From Maine to Washington, a growing number of states are taking on the issue of genetically engineered foods, fanning the flames of a decades-old debate about whether the products are dangerous to human health.

This month, Connecticut became the first state to pass a law requiring the labeling of food made from genetically modified organisms (GMOs). In May, the Vermont House passed a similar bill, which will now be taken up by the Senate. Right to Know GMO , a self-described grass-roots coalition with members in 37 states, counts 26 states that have introduced labeling bills.

In Washington state, a referendum on GMO labeling is scheduled for November. Last November, a referendum in California failed 53-47 after the biotech industry spent nearly $45 million on opposition ads.

At the federal level, Sen. Barbara Boxer, D-Calif., introduced a bill in April â?? separate from the farm bill â?? that would direct the U.S. Food and Drug Administration (FDA) to "clearly label" genetically engineered foods. Boxer notes she has 11 co-sponsors of the bill, which she first introduced in 2000. Rep. Peter DeFazio, D-Ore., introduced the House version.

Boxer also attached two amendments to the farm bill, one saying that the United States should join the 64 other nations, including those in the European Union, that have labeling requirements for genetically engineered foods. The other amendment requires a report in six months from several federal agency heads reviewing the labeling methods used internationally, and the "probable impacts" of having differing labeling requirements passed by states rather than a federal standard.

"As more and more states take action, I believe lawmakers in Washington will realize that Congress and the FDA must ensure that all Americans know what's in the food they're eating," Boxer said in an e-mail.

"The companies have such complete control over who can do independent research into the nature of these things and their impact that we really don't know very much," said Andrea Stander, executive director of Rural Vermont, a non-profit farm advocacy group. "We don't know nearly as much as we should."

The FDA ruled in 1992 that genetically engineered foods are not "materially different" from their traditional counterparts and therefore do not have to be labeled, a ruling opponents of GMOs won't accept.

Monsanto, based in St. Louis, Mo., is a leading supplier of seeds for genetically engineered crops to farmers in the United States and around the world, and a frequent target of protests against GMOs. The company has clearly stated why it is opposed to labeling, saying mandatory labeling "could imply that food products containing these ingredients are somehow inferior to their conventional or organic counterparts."

About 90% of the corn, cotton, soybeans and sugar beets grown in the United States are genetically engineered, according to BIO, the trade group representing Monsanto, Bayer, Dow, DuPont and other giant firms that dominate the industry.

The modifications to the DNA of seeds, which started in the mid-1990s, fall into two categories: seeds that have built-in genetic resistance to insects, forgoing the need for insecticides, and seeds that tolerate herbicides, making it possible to spray crops, such as soy beans, that are prone to weeds.

Genetic engineering is the fastest growing technology in the history of agriculture, with upward of 17 million farmers around the world using genetically altered seeds, BIO spokeswoman Karen Batra said.

The problem with requiring labels on genetically engineered foods, Batra said, is that they would imply those foods are unsafe.

"In the United States, food packaging labels are reserved to convey food safety information about allergens that might be in a food or to convey nutritional composition," she said. "If the federal government were to mandate by law that a particular food product needed to be labeled that would infer it would be for a safety reason."